When Japan attacked in the Pacific in December
1941, he was commander of U.S. Far East Air Force, based in the
Philippines. What had been described as a breakdown in communications
with McArthur's Headquarters enabled the enemy to catch Brereton's
Luzon-based B-17s on the ground and the bulk of his force was
destroyed.

He later assumed command of the Middle East Air Forces, which later became
the 9th Air Force Army. Achieving the rank of Lieutenant General in
April 1944, he commanded the 9th Air Force when it raided Ploesti,
Rumania, and remained with it until August 1944, at which time he took
over the 1st Allied Airborne Army in Great Britain.